1. Field of the Invention
The present invention relates to devices, systems, and processes useful to treat obesity in patients, and more specifically to the treatment of the morbidly obese.
2. Brief Description of the Related Art
According to the Centers for Disease Control (CDC), the United States is in the midst of an epidemic of obesity (Mokdad A H, Serdula M K, Dietz W H, Bowman B A, Marks J S, Koplan J P, “The spread of the obesity epidemic in the United States 1991-1998”, JAMA 1999; 282: 1519-22). More than half of the U.S. population is overweight. One third of it is classified as obese, with more than 5 million adults in the U.S. having a body mass index>40 (BMI=weight in kg/height in meters). Ten million more are near that mark and may be at risk for obesity-related health problems. The problem is increasing; obesity in children and adolescents increased two-fold in the last decades. Obesity is associated with increased cardiovascular disease risk (Mokdad A H, Ford E S, Bowman B A, Dietz W H, Vinicor F, Bales V S, et al, “Prevalence of obesity, diabetes, and obesity-related health risk factors, 2001”, JAMA 2003; 289: 76-9) and mortality (Fontaine K R, Redden D T, Wang C, Westfall A O, Allison D B, “Years of life lost due to obesity”, JAMA 2003; 289: 187-93; Crespo C J, Palmieri M R, Perdomo R P, Mcgee D L, Smit E, Sempos C T., et al., “The relationship of physical activity and body weight with all-cause mortality: results from the Puerto Rico Heart Health Program”, Ann. Epidemiol. 2002; 12: 543-52). According to the Social Security Administration (SSA), $77 million are paid monthly to approximately 137,000 persons who meet obesity requirements for disability.
After smoking, obesity is the second most preventable disease causing death. Approximately 300,000 Americans die every year, and millions more suffer, due to obesity-related co-morbidities. These include, but are not limited to, hypertension, cardiac disease, dyslipidemia, diabetes mellitus type 2, stroke, sleep apnea and other respiratory disorders, arthritis of weight-bearing joints, gallbladder disease, gastro-esophageal reflux, stress urinary incontinence, infertility and hormonal imbalances, skin disorders, and some types of cancer.
Depression, low self-esteem, societal rejection and prejudice, lesser work and income opportunities, marital, familiar, social and sexual problems add to the burden of the morbidly obese. Approximately $100 billion is spent annually in the United States for the treatment of these obesity-related diseases. An almost equal amount is spent yearly in diets and low-calorie foods and drinks, exercise programs and other weight loss treatments which, even if successful, offer only temporary relief.
There are ten times as many candidates for obesity surgery in the U.S. as for heart bypass surgery annually. The American Society of Bariatric Surgery has only 500 members who perform gastric-bypass operations. Waiting lists are months long.
Several surgical methods have been tried to help those with morbid obesity to lose weight. Various small bowel and stomach operations were tried. Often, these attempts had high complication rates and did not result in significant weight loss. The currently used surgical method of bariatric surgery involves surgical separation of the majority of the stomach from the intestinal tract, and stapling of the gastric remnant to allow very little capacity to store food. The small intestine is anastomosed to the stomach, and the gastric contents empty directly into the jejunum, bypassing the duodenum. Although initially people who undergo this operation may have symptoms associated with eating, usually their appetite gradually decreases for poorly understood reasons. Because of the frequency of morbid obesity in our population, the demand for this operation greatly exceeds the supply. There may be as many as 2 million people in the U.S. who would be candidates for this operation. Most practitioners who offer this procedure are booked many months ahead and can't keep up with the demand. It is likely that one day this will be one of the most frequently performed operations, and exceed the volume of coronary artery bypass graft procedures (250,000 cases/year).
Despite being performed in patients often in their 20's or 30's, the surgery is associated with substantial morbidity and an approximately 1% death rate. Patients with morbid obesity are not ideal for major abdominal surgery. Major complications are observed in 20% of patients, and death occurs in 0.3-1%. This is tragic because often the patients are very young. Additionally, significant permanent weight loss occurs in only 80%.
Weight loss, on the other hand, is sometimes associated with an uncommon vascular condition, chronic mesenteric ischemia. Patients with chronic mesenteric ischemia have blockages in arteries that supply the gut. While they have enough blood flow to keep the small intestine alive at rest, they can't achieve the 3-fold increase in blood flow required after eating for the intestine to fully function. They experience abdominal pain after eating, often accompanied by weight loss and diarrhea after eating. They adapt their eating to avoid these symptoms, namely by eating small amounts frequently. After a while, their appetites are decreased and they no longer crave food. For example, there are some adult patients with mesenteric ischemia who weigh 80 pounds and are cachectic, but are not hungry.
Patients with chronic mesenteric ischemia are usually older and classically have atherosclerotic stenosis or occlusion of all three arteries supplying the bowel, including the celiac axis, the superior mesenteric artery, and the inferior mesenteric artery. However, when collaterals are not well-developed, patients can be symptomatic with involvement of only the artery that supplies the small bowel, the superior mesenteric artery.